Spasms-plug



W. BURR/IAN.A

SPARK PLUG.

APPLICATION FILE/o ocT. s1. aan.

1,31 1,@39, Patented J uly 22, 1919.

' of the rotary cap,

lTALFR/ED BUBldEl, FVVRGESTER, MASSACHUSET maman-.wu-

Patented July 22, lzlli.

Application led October S1, 191?. Serial No. 199,557.

scription of the invention, such as will en able others skilled in the art to which it appertains to make and use the same.

vThis invention particularly resides in and relates to spark plugs for internal combustion engines, and it is one of the objects ofthe present invention to provide a variable spark gap and also provide a spark gap which is rendered visible so that it may be readily seen during the operation of the ma tor upon which the spark plug is mounted.

A further object ot the present invention is to provide means permitting the space adjustment and variation of the spark gap forming devices so that the intensity of the spark may be controlled.

1t is another object of the present inven tion to provide a dust guard or a shield dis posed adjacent to the exposed spark gap for the purpose of preventing the accumulation of dirt or dust at the exposed gap.

Other objects which are rendered manip fest in the following specification and will be readily apparent to those skilled in the art, are contemplated by the present inven tion, one form orn which is illustrated in the accompanying drawing, wherein,

Figure l is a side elevation partly in section of the improved spark plug,

Fig. 2 is a side elevation of the detached dust guard,

Fig. 3 is a side elevation partly in section Fig. t is a side elevation partly in section of the bushing. p

The spark plug may comprise any suitW able form of core 2 oi' insulating material such as porcelain having a central iXed electrode 3 projecting below the bottom end of the spark plug, the upper end ot the core 2. being provided with a` chamber alining with the Xed electrode 3, the chamber being provided with lateral openings forming windows 4 through which the upper end of the liXed electrode is visible. rlhe core is incased in a suitable shell or plug torming member 5 having screw threads at its lower end at 6 to be screwed into an engine casing, the shell being provided with a lat eral electrode 7 having a point directed to` ward the fixed electrode 8. A suitable lock nut 8 is threaded into the upperend of the shell or plug 5 to hold the core in position, the lock nut 8 also being provided vwith an outwardly extended threaded portion 9 to be engaged by a cylindrical shield or guard 10 designed to permit observation of'sparks formed atthesupper end of the fixed ele-ctrode 3 at the windows t. `Preferably the guard or shield 10 is of non-conducting material and is shown as being perforated or may be formed of a transparent or other material if desired.

vThe upper end of the core 2 is provided with a reduced neck 11 and a head l2 upon which there is seated a ixed bushing 13 centrally threaded as at lf-l, the bushing having a relatively thin flange which is spun or pressed into the neck 11 and there- Iby held in position on the spark plug. The bushing isshown as provided with a shoulder 15 about which there may be spun down the flange of a cap 16 which latter has an upwardly extending stem portion 17 to re ceive-a knob 1 8 which preferably is made of non-conducting material such as hard rubber or ber and may be pinned or otherwise fastened to the cap 16 so that the latter may be rotated as desired about the bushing 13 on which it is mounted.

The cap 16 is provided with a central polygonal or otherwise suitably shaped socket 19 to fit the head or adjacent end of a screw 2O whichxis threaded in the thread 14 of the-bushing 13 and which preferably is provided with a reduced point 21 and which forms a movable electrode section disposed in juxtaposition to the upper end of the fixed electrode 3, adjacent the window or windows 4, in the core 2. Gbviously the point 21 of the movable electrode section 20 may be tipped with platinum or other suitable material for purposes well known.

` The cap 16 abovedescribed is freely rol.

tatable on the bushing' 13 and byl rlits engagement at the socket 19-with the head of the electrode section 20, when the cap is rotated, the threaded electrode section is advanced or withdrawn in the bushing 13 thereby varying the distance between the point 21 and the upper end of the fixed electrode 3 and thereby controls the in tensity of the spark. 'lt is desirable that suitable means be provided to temporarily llo,

^ the spark While the p ug is in service.

lock or secure the cap 16 With relation to the bushing 13, to hold the spark in respective adjusted position and for this purpose any simple means may be utilized, as for instance, employing a ball 25 which may be mounted .in an aperture 26 formed for its reception in the body of the bushing 13 normally pressed outwardly by a spring 27 so that it is adapted to snap into one o3 a series of apertures suitably formed at 28 in the flange of the cap -16 which surrounds the head of the bushing 13.

From the above it will be seen that I have provided an extremely simple, practicable, substantial and durable device providing an exterior spark gap providing for the observation of the spark, during the operation of the device, and also providing for the safe adjustment of the parts to change the length of the gap during the operation of the engine or current flow through the spark plug` Further there is provided a simple means for preventing the access and the accumulation of dust or dirt around the exterior spark gap by means of the dust guard or shield.

What is claimed is:

1. A spark plug having a windowed core, a threaded bushing fixed to the head of the .core, relatively adjustable electrode sections having their adjacent tips visible through Windows in the core, one section threaded in -said bushin andan insulated socket member turnab y mounted on said bushing for turning said threaded section to vary ap between the electrode tips .i 2. A sparkplug having a core with a window in its body, relatively adjustable electrode sections forming a spark gap at the Window, and ratchet means for varying the gap While 'the plug is in service, said 4means comprising a Vbushiiug lfixed on the head of the core, one section being thread- Lei ipse ed in said bushingand having` a polygonal head, and insulated cap with an annular series of seats, and a resilient latch'mount-v ed in said bushing, the cap non-rotatably y' but slidably engaging the polygonal hea of the adjustable electrode section.l

3. A spark plug havingan opaque core with radial windows and a central bore,

va fixed electrode section in the core and a perforated sleeve surrounding and spaced from the core, 'a fixed threaded bushing on the upper end of the core, an upper threaded electrode engaging said bushing` and adjustable toward or from th'; ,i Velectrode and forming a spark gapat said'ywindows, a4

Acap having` a Hangs turnably Hitting the aushing, and means for interlocking the cap ind bushing, said cap operatively engaging threaded into the core and seating against the Hangs, and terminating at the shoulder of the core belovsr the neck; an internally threaded bushing fitting over the neck andA clenched rigidly into its reduced portion; a threaded electrode section engaging the threads of the bushing and having its lower end extended into the core and having at Aits upper end av non-circular portion; am

insulated cap irremovably and turnably mounted on the bushing and having a recess complementary to the head of the' upper or threaded electrode so as to turn the latter, and a lower electrode forming with the upper one a gap in juxtaposition to its Window.

ln testimony whereof I aliix my signature.

WALFRED BURMAN.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patente,

' Washington, D. C. 

